International audienceDespite the high level of automation, the practicability of formal veri cation through model-checking of large models is hindered by the combinatorial explosion problem. In this paper we apply a novel context-aware veri cation technique to the Landing Gear System (LGS). The idea is to express and verify requirements relative to certain environ- mental situations. The system environment is decomposed into several independent scenarios (contexts), which are successively composed with the system during reachability analysis. These contexts are speci ed us- ing a language called CDL (Context Description Language), based on activity and message sequence diagrams. The properties to be veri ed are speci ed with observer autom...